This program seeks to develop a one year biodegradable estrogen/progestin implant for postmenopausal hormone replacement therapy. The program will utilize a proven hormone combination, estradiol and levonorgestrel. It has been shown that side effects of estrogen therapy can be lowered by administering a progestin with the estrogen. Both hormones will be incorporated into an innovative implant design already under development by BIOTEK to deliver pure levonorgestrel as a maintenance contraceptive. The new implant is thermoformed from very high molecular weight poly-L-lactide, using a method which minimizes degradation during manufacture. The implant has a hormone-loaded outer shell for efficient drug delivery and a pure polymer core for mechanical strength. The implant will biodegrade if left in place for more than one year, but it can be surgically removed for medical reasons at earlier times. With no need to keep track of daily dosing, and little reason to anticipate an unpleasant removal episode, both women and doctors should welcome such implants as a convenient new form of estrogen replacement therapy combining almost effortless compliance with stable hormone levels. PROPOSED COMMERCIAL APPLICATIONS: The proposed work involves incorporating a drug into the outer portion of a strong, easily administered implant which biodegrades when left in the body for more than a year. The same technique could be useful for delivery of other chronically administered hormones and maintenance medications.